How to store values in a matrix to plot later?

I am trying to create a pandemic simulation to account for several variables, store these values in a single matrix, and then plot these values on a graph. I'm having some trouble with this. My graphs are not showing up as expected and I'm not sure what the problem is. Please help. Thanks.

Here's my code:

%Epidemic Simulation
%Author: James Metz
%Date: Nov 15, 2020

%Define Natural Paramteres:
p = 0.0144; %Natural Birth Rate (Davidson County)
u = 0.008; %Natural Death Rate (Davidson County)
f = 0.03; %Infection Rate
r = 0.075; %Recovery Rate
m = 0.0001; %Death due to Infection Rate
v = 0.092; %Vaccination Rate

%Define Evaluation Time Paramteres:
dt = 1; %Time increments (days)
tEnd = 365; %Simulation length (days)
t = 1:dt:tEnd;

%Initialize Variables: 
I = 10; %Initial infected population
R = 0; %Initial recovered population
S = 692587; %Initial susceptible population
I_1d = zeros(1, tEnd); 
R_1d = zeros(1, tEnd); 
S_1d = zeros(1, tEnd); 

S_1d(1) = 692587;
I_1d(1) = 10;
R_1d(1) = 0; 

%Loop through times:
for idx = 2:dt:tEnd
    %Initialization:
    S = S_1d(idx - 1); 
    R = R_1d(idx - 1); 
    I = I_1d(idx - 1); 
    %Find changes in population numbers
    dS_dt = -f*S*I - S*u - S*v + S*p; %Drop in unifected population
    dI_dt = f*S*I - r*I - m*I - u*I; %Drop in infected population
    dR_dt = r*I + S*v - u*R; %Gain in Recovered population
    %Store new values:
    S_1d(idx) = S_1d(idx-1) + dS_dt; 
    R_1d(idx) = R_1d(idx-1) + dR_dt; 
    I_1d(idx) = I_1d(idx-1) + dI_dt; 
end

figure(1)
subplot(2,2,1)
plot(t, S_1d)
xlabel('Time (days)')
ylabel('Susceptible Population')
title('Drop in Susceptible Population due to Infection')
subplot(2,2,2)
plot(t, R_1d)
xlabel('Time (days)')
ylabel('Recovered Population')
title('Recovery Rate of Infected Persons')
subplot(2,2,3)
plot(t, I_1d)
xlabel('Time (days)')
ylabel('Infected Population')
title('Infection Rate of Susceptible Persons')
subplot(2, 2, 4)
plot(t, S_1d, 'green')
plot(t, R_1d, 'Blue')
plot(t, I_1d, 'red')


my graphs look like this: 

[Stephen23]

https://web.archive.org/web/20201126154919/https://www.mathworks.com/matlabcentral/answers/662368-how-to-store-values-in-a-matrix-to-plot-later

Answer 1

[Sibi]

Try this , you should not multiply the infected population to sucesptible population

   dS_dt = -f*S - S*u - S*v + S*p; 
    dI_dt = f*S - r*I - m*I- u*I; 
    dR_dt = r*I + S*v- u*R; 

[James Metz]

The equations are based on the SIR model.

See link for more information: https://www.ijraset.com/fileserve.php?FID=9443

But thank you.